EP2212122A1

EP2212122A1 - Securing of documents by means of digital watermark information

Info

Publication number: EP2212122A1
Application number: EP08843738A
Authority: EP
Inventors: Edward Springmann; Manfred Paeschke; Oliver Muth
Original assignee: Bundesdruckerei GmbH; Bayer MaterialScience AG
Current assignee: Bundesdruckerei GmbH; Covestro Deutschland AG
Priority date: 2007-10-31
Filing date: 2008-10-31
Publication date: 2010-08-04
Anticipated expiration: 2028-10-31
Also published as: US20110007934A1; JP2011500393A; WO2009056353A1; PL2212122T3; CN101918224B; KR20100106323A; EP2212122B1; KR101515666B1; BRPI0818479B1; BRPI0818479A2; US8478080B2; JP5274568B2; DE102008012426A1; KR20150008507A; CN101918224A

Abstract

The invention relates to the production of a document (1), wherein image information is incorporated into a plurality of layers (15, 17, 19) of the document (1) such that the pieces of image information are combined into a total image. The image information in at least two of the layers (15, 17, 19) comprises digital watermark information (25, 27, 29), wherein the entirety of the digital watermark information (25, 27, 29) in the at least two layers (15, 17, 19) forms a security feature for an authentication of the document (1). The invention further relates to a respective document (1), a method for authentication (37), and a device for authentication.

Description

SECURING DOCUMENTS USING DIGITAL WATERMARK INFORMATION

Field of the invention

The invention relates to a method for producing a document, a document produced according to the method, an authentication method for determining whether the document is authentic, and an authentication device. The document is in particular a security and / or value document.

Prior art and background of the invention

Security and / or value documents in many cases comprise individualizing (in particular personalizing) information which represents an assignment of the security and / or value document to an issuer, a group of persons or the person of the document holder. As personalizing information is particularly suitable image information, such as a passport photograph, a fingerprint or other biometric features, but also alphanumeric strings, such as name, address, place of residence or date of birth of the person.

Examples of security and / or value documents are identity cards, passports, identity (ID) cards, access control cards, visas, tax stamps, tickets, driver's licenses, motor vehicle documents, banknotes, checks, postage stamps, credit cards, any smart cards and adhesive labels (for example for product security).

From the prior art, different methods for the production of value and / or security documents are known. For example, US Pat. Nos. 6,022,429, 6,264,296, 6,685,312, 6,932,527, 6,979,141 and 7,037,013 describe such processes in which ink-jet printing is applied to blanks which are coated with a protective lacquer or protective film as protection against mechanical and / or chemical damage Damage and tampering should be protected. With this method, personalizing and / or individualizing information can be stored in color in the security and / or value document by printing technology. The resulting security and / or Value documents, however, have only a relatively low security against manipulation, because the printed information is completely printed relatively near the surface and the protective layer of lacquer or a protective film usually no monolithic, cohesive connection with the card blank forms and thus removable and / or removable. Subsequent manipulation of the printed matter is possible.

DE 41 34 539 A1 discloses a recording medium with colored image information, which is in particular a value or identity card, as well as a method for the production thereof. The image information is decomposed into a light / dark part and a color part. The light / dark portion, which is intended for the visual impression, is introduced into the recording medium in highly resolved form. This proportion is superimposed on the color image information congruent, so that an integral overall impression is created. In order to ensure the security against counterfeiting, one of the parts of the image information is introduced into a card structure. Embodiments are described in which, for example, the light / dark information is introduced by laser engraving into a transparent film which is applied to a printed ticking. On a applied to the film ink-receiving layer or the transparent film, the color component is printed. In another embodiment, the inlay is provided with the color components of the image information by electrophotographic means. Over the colored fixed toner image, a thin transparent cover film is then arranged, in which the light / dark portion of the image information is baked by means of a laser beam writer. A further embodiment provides that the inlay is provided with black / white information using a conventional method such as ink jet printing and is covered in the following step with a substantially transparent plastic film, which is suitable for recording migrating colors. The colored image components are introduced by means of migrating colors into the depth of the cover layer. The cover film can first be printed with the colored image information. Under the influence of heat, the ink migrates into the interior of the cover layer until UV radiation initiates crosslinking of the cover layer, which stops further migration. In yet another embodiment, the color information is first introduced into the cover layer and subsequently light / dark information is applied using conventional printing methods. Again, there is the problem that the film used, under or in which part of the information is arranged, does not form a monolithic connection with the tick and therefore can be removed and / or replaced for counterfeiting. In a number of the described Embodiments, moreover, a part of the information is applied directly to the surface and a forgery and / or manipulation particularly easily accessible.

The documents US Pat. No. 7,005,003 B2, EP 0 131 145 B1, US Pat. No. 5,734,800 and US Pat. No. 6,765,693 B1 describe methods for printing colored images with different color separations.

In particular, security documents are often issued by the issuer as a card whose supporting components are made of plastic. Polycarbonate has proven to be particularly resistant. Such documents should in particular be protected against imitation or it should be reliably detectable that a certain copy was actually issued by the alleged issuer.

To secure documents with image components, such as Passport pictures or reproductions of passport pictures or pictures, which refer not to the owner of the document, but to the document type (for example special logos), are known to introduce digital watermarks in the picture. The method of introducing digital watermarks is based on a modification of the original image information. In general, the watermarks for the viewer are not or barely perceptible information. For example, US 2002/080996 A1 describes a method and systems for embedding binary data in security documents and related methods and systems for detecting / decoding such data.

The document according to the present invention may e.g. As described in the preceding paragraphs, be constructed and / or have one or more of the aforementioned features.

Objects of the invention

It is an object of the present invention to provide a method of producing a document which increases the security against counterfeiting. Furthermore, a corresponding document should be specified. Another task of the present The invention is to provide an authentication method for determining whether a document is authentic and an authentication device.

Broad features of the invention and preferred embodiments

According to a basic idea of the present invention, watermark information is introduced into the image information of at least two different layers of a document, and the watermark information is designed such that only the entirety of the watermark information in the at least two layers constitutes a security feature for authentication of the document.

By the term "layer" is meant a mostly planar area in a document that is defined in a direction transverse to the plane or layer by its position in the document, for example, the layer extends to a marketable card-shaped document, eg, an identity card , at a constant distance from the surface of the map.

From the term "layer" the term "substrate" is to be distinguished. For example, in a standard map document, e.g. Several substrates or layers of material are laminated together, so that they give a composite material. In principle, it is possible that even a single layer contains two or even more than two layers in which image information for the overall image is located. In particular, a first layer may lie through a first surface of the substrate, a second layer through a second surface of the substrate on the opposite side, and a third layer within the substrate. However, in practice, it may happen that e.g. When printing a surface printing materials also penetrate into the interior of the substrate. Therefore, a layer will usually contain only a maximum of two layers of image information.

Some of the features of the invention described below relate to a production method, a document produced in the production method, an authentication method and / or an authentication device. If a feature refers to several such categories, but the feature is actually described in more detail only in one category, the description applies accordingly to the other categories as well. The entirety of the watermark information in the at least two layers can be formed in different ways. In other words, the entirety of the watermark information can be divided into parts in different ways and introduced into the individual layers. In the decomposition, the watermark information may be provided with other additional information so that the entirety of the watermark information in these cases does not merely result from simply joining the watermark information in the at least two layers. As will be explained in more detail below, the additional information may be information about where and / or in which layers other partial information of the entirety is located and / or how to proceed in the evaluation of the partial information, about the entirety of the watermark information to obtain.

Not only in the evaluation, but also in the detection of the watermark information contained in the individual layers can proceed in different ways. Thus, in a first embodiment it is possible to detect only the watermark information in the individual layers separately from one another and to form the entirety of the watermark information therefrom in accordance with a prescribed rule. In a particular embodiment, however, an additional summary detection of watermark information can take place in at least two layers. If, for example, the image information in a first layer is represented exclusively by a first color and the image information in a second layer is represented exclusively by a second, different color, the watermark information from the individual layers can be detected by color-selective detection. A summary detection of the watermark information in both layers is done for example by a non-color-selective detection. The summary detection usually contains less information than can be obtained by processing the information from different layers. However, the aggregated multi-layer information may also contain additional information that is not obtained by acquiring the information in the individual layers. One reason for this is that, depending on the detection method, not all the information contained in a layer is captured in all cases. For example, in the case of an optical detection, one reason for this may lie in the fact that further layers whose information is not to be detected disturb the detection and / or the Capture is not sensitive to the entire spectrum. Another reason may be that part of the information contained in a layer can only be detected if substances in the layer are excited by irradiation with electromagnetic radiation of a specific wavelength and therefore emit radiation of characteristic wavelength. Such a fluorescence makes it possible to detect at which points the fluorescent material is located.

In a particular embodiment, the watermark information in at least one of the layers is introduced only in a partial area of the image area. The picture surface is understood to mean the surface within a layer in which the image information is located. Since the watermark information is only in the subarea, finding it is difficult for a viewer who is not previously informed. For the informed viewer or user of readout devices, however, the detection and further processing of the watermark information is facilitated and improved by the knowledge of the subarea if the subareas in which watermark information is located do not lie in different layers or at least do not completely overlap one another. It is e.g. possible to detect and / or evaluate the subareas with the watermark information with a higher resolution than the other image areas. The subregions with the watermark information can also be selected such that their particular optical detection from a direction that is perpendicular to the layer plane is not obstructed by substrate material or printed matter in other layers.

If, in at least one of the layers, the watermark information is introduced only into a partial area of the image area, a particularly advantageous procedure is possible in which the watermark information in a first layer contains information on which partial area in the first layer or in a second layer other watermark information is arranged and / or how the watermark information is to be evaluated in the second layer and / or in another subregion of the first layer. In particular, if secret rules are defined as to evaluate the watermark information in the first layer (containing the additional information about the device or evaluation), a potential counterfeiter can not access the entirety of the watermark information. For example, in the case of personalized documents, the watermark information can also be personalized. If the potential forger the principle, such as the personalization of watermark information can not recognize, he also can not create a correctly personalized document for another person.

The watermark information is preferably digital, in particular not or at least not with the untrained eye perceptible watermark information, i. the observer can not recognize that there is watermark information in the image when viewing the image composed of the image information of the individual layers. The introduction of watermark information into image information (in particular image information introduced by digital printing in the document) is known per se. A document describing such methods has been given above. In the description of the present invention, therefore, the production of watermark information and the incorporation of watermark information into image information will not be discussed in detail.

Preferably, the watermark information, which is incorporated in different layers, only in its entirety constitutes an evaluable authentication information. In other words, the watermark information from only one layer or not all layers and / or not all sub-regions in all layers in which watermark information is located is not sufficient to determine whether the document is authentic. Moreover, the watermark information, if not in its entirety, is not evaluable, i. it can not be a part of the total evaluated. An evaluation means that a result can be determined. An example of such a design is a set of information that i.a. is evaluated by the fact that a total checksum is calculated. If a part of the whole is missing, the checksum can not be calculated.

As this embodiment shows, the invention is at least partially dependent on predetermined rules as to how to proceed with the overall watermark information contained in the document. Part of the method for producing a document is therefore also, for example, a method step in which the watermark information, taking into account the evaluation rule and / or the rule for acquiring the watermark information from the document, is first processed such that after the watermark information has been introduced into the document Document a capture and / or evaluation actually leads to the desired result.

However, apart from the embodiment described above, the invention also includes an embodiment in which a subset of the totality of all the watermark information incorporated in the document can also be evaluated. For example, For example, information about the document holder, issuer, or document (e.g., document number) can be obtained from the watermark information included in a first layer or in a first subregion of any layer by evaluating that subset.

In a preferred embodiment, the image information in the individual layers of the document are represented by a different color in each case. If the base colors of a color system or color space (such as red-green-blue, RGB, or cyan-magenta-yellow-black, CMYK) are used in a manner known per se, preferably at most one of the base colors is used for each of the layers, in any case so far it concerns a particular image formed by the color information in the individual layers.

The assignment of a color to the respective layer increases the security against counterfeiting, since an unambiguous assignment of the watermark information to the respective color is thus also established. In addition, the color can be used to selectively capture the watermark information of a particular layer, e.g. using color filters during optical detection.

"Colors" in a particular embodiment of the present invention are also understood to mean "shades of gray". For example, a dark gray tone is used in a first layer and a light gray tone is used for the image information in a second layer. However, this makes it difficult to optically capture the image information selectively in the individual layers.

In this description, colors are used when the optical effect is described. If, on the other hand, the production of a printed image is described, one speaks of printing materials (eg inks) which have the respective color. The overall picture may be z. B. act a passport photograph or a logo. Under a BIId ₁ which is formed by image information in a plurality of layers is, however, understood, any other obtainable by printing on a substrate structuring the purposes of this description. For example, text can be designed graphically and printed from multicolored letters.

In the case of the document, image information is / are introduced in each case in a plurality of layers of the document, so that the image information is supplemented to form an overall picture. The positions of the layers are preferably defined by surfaces of different substrates.

For example, the overall image information is decomposed into at least two print separations, the z. B. each contain a partial information of the overall picture. The print separations are also impressed with the watermark information. Then the at least two print separations are printed on at least two different substrate surfaces, so that the printed print separations fit over each other and together make up the overall picture.

For example, the (in particular layered) substrates can be joined together by lamination. The at least two print separations are in these cases printed in at least two spaced-apart planes, but not necessarily on as many different substrates as layers containing image information.

In particular, the present invention relates to a document which has a composite of polymer material layers, which may optionally also contain layers of other materials, for example of cardboard or paper. The association serves in particular for the production of security and / or value documents.

In particular, the document may have a Polymermateriallagenverbund z. B. is welded in transparent protective films. In addition to the polymer material (s), other elements and devices may be part of the document, e.g. B. a microchip and an antenna structure for wireless readout of the microchip. Further, other materials may be incorporated in the polymeric material, e.g. B. secret additives. The image information can be printed in a manner known per se on individual layers of the document, in particular of the polymer material laminate, or printed. A preferred printing method is ink-jet printing or another digital printing method, since with digital printing documents can be personalized in a simple manner, ie, for example, personalized for the person of the future document holder (eg by printing a passport photograph).

Basically, as materials for the polymer material layers z. B. all common in the field of security and / or value documents materials used. The polymer material layers can, identically or differently, be based on a polymer material from the group comprising PC (polycarbonate, especially bisphenol A polycarbonate), PET (polyethylene glycol terephthalate), PMMA (polymethyl methacrylate), TPU (thermoplastic polyurethane elastomers), PE (polyethylene), PP (Polypropylene), PI (polyimide or poly-trans-isoprene), PVC (polyvinyl chloride) and copolymers of such polymers. Preference is given to the use of PC materials, wherein, for example, but by no means necessarily, so-called low-T _g materials are used, in particular for a polymer material layer on which a printing layer is applied, and / or for a polymer material layer, which with a Polymermateriallage , which carries a print layer, is connected on the side with the print layer. Low-T _g -Materials are polymers whose glass transition temperature is below 140 ⁰ C.

The polymer material layers can be filled or unfilled. The filled polymer material layers contain, in particular, color pigments or other fillers. The polymer material layers can also be dyed with dyes or colorless and, in the latter case, transparent or translucent.

It is preferred in this case if the base polymer of at least one of the polymer material layers to be joined (to obtain the document or the layer composite by lamination) contains the same or different mutually reactive groups, wherein at a laminating temperature of less than 200 ^° C. reactive groups of a first polymer material layer with one another and / or react with reactive groups of a second polymeric material layer. This can reduce the lamination temperature without endangering the intimate bond of the laminated layers. In the case of various polymer material layers with reactive groups, this is due to the fact that the various polymer material layers can no longer be readily delaminated due to the reaction of the respective reactive groups. Because between the polymer material layers takes place a reactive coupling, as it were a reactive lamination. Furthermore, due to the lower lamination temperature, it is possible to prevent a change in a colored printing layer, in particular a color change, from being prevented. In particular, therefore, it is also possible to accommodate with the naked eye unrecognizable watermark information in the printed image.

It is advantageous if the glass transition temperature T ₉ of at least is a polymer material layer prior to thermal lamination is less than 120 ⁰ C (or even less than 110 ° C or less than 100 ⁰ C), wherein the glass transition temperature of this polymer material layer after the thermal lamination by Reaction of reactive groups of the base polymer of the polymer material layer with each other by at least 5 ° C, preferably at least 2O ⁰ C, higher than the glass transition temperature before the thermal lamination. In this case, not only is a reactive coupling of the layers to be laminated together. Rather, the molecular weight and thus the glass transition temperature are increased by crosslinking of the polymer within the layer and between the layers. This complicates delamination in addition, since, for example, the printing inks are irreversibly damaged, in particular in a manipulation attempt by the high delamination temperatures necessary and the document is thereby destroyed. The lamination temperature when using such polymer materials is preferably less than 180 ^° C., more preferably less than 150 ^° C. The selection of suitable reactive groups is possible without difficulty for a person skilled in the art of polymer chemistry. Exemplary reactive groups are selected from the group consisting of -CN, -OCN, -NCO, -NC, -SH, -S _x, -Tos, -SCN ₁ -NCS ₁ -H, -epoxy (-CHOCH _2), - NH ₂ , -NN ⁺ , -NN-R ₁ -OH, -COOH, -CHO, -COOR, -HaI (-F, -Cl, -Br, -I), -Me-HaI (Me = at least divalent metal , for example Mg), -Si (OR) ₃ , -SiHaI ₃ , -CH = CH ₂ , and - COR ", where R" can be any reactive or non-reactive group, for example H ₁ Hal, C ₁ -C _2O -alkyl, C ₃ -C ₂₀ -aryl, C ₄ -C ₂₀ -ArAlky I, in each case branched or linear, saturated or unsaturated, optionally substituted, or corresponding heterocycles having one or more identical or different heteroatoms N, O ₁ or S. Other reactive groups are of course possible. These include the reaction partners of the Diels-Alder reaction or a metathesis.

The reactive groups may be attached directly to the base polymer or linked to the base polymer via a spacer group. Suitable spacer groups are all spacer groups known to the person skilled in the art of polymer chemistry. The spacer groups may also be oligomers or polymers which impart elasticity, whereby a risk of breakage of the security and / or value document is reduced. Such elasticity-promoting spacer groups are known to the person skilled in the art and therefore need not be further described here. By way of example only, spacer groups may be mentioned which are selected from the group comprising - (CH ₂ ) _n -, - (CH ₂ -CH ₂ -O) _n -, - (SiR ₂ -O) _n -, - (C ₆ H ₄ J _n -, - (CeH ₁₀ ) ,, -, dC-alkylene, -C ₃ -C _{(n + 3} rArylen-, -C ₄ -C _{(n + 4)} -ArAlkylen-, each branched or linear, saturated or unsaturated, optionally substituted, or corresponding heterocycles having one or more identical or different heteroatoms O, N, or S, where n = 1 to 20, preferably 1 to 10. Regarding further reactive groups or possibilities of modification is to the reference "Ullmann ^'s Encyclopaedia of Industrial Chemistry", Wiley Verlag, electronic edition 2006. In the above discussion, the term "base polymer" refers to a polymer structure which does not carry any reactive groups under the lamination conditions used, which may be homopolymers or copolymers In contrast to the polymers mentioned, mod comprises polymers.

It is advantageous if the respective layers are arranged in a polymer material multilayer composite on internal layers of the composite, i. H. Layers that do not form the surface of the layer composite. In this case, counterfeiting or falsification of printing layers serving as security features is made difficult or even impossible. This is also advantageous for the unchanged preservation of the watermark information.

However, in this case there is the problem that conventional card-shaped data carriers can be delaminated relatively easily by manipulation. In the event that a security feature (eg at least part of the total watermark information) is applied by means of printing technology processes on an inner layer of the layer composite, it can be achieved that the Printing materials contain binders which at least substantially consist of the same polymer as the material of the layers of the layer composite. In this case, the risk of delaminations is virtually eliminated because when laminating a monolithic composite of the individual layers is formed. It is particularly preferred if the printing materials contain binders based on polycarbonate, if at least some of the layers of the composite likewise consist of polycarbonate. In the latter case, the printed materials are printed on inner layers of the layer composite, wherein in particular all layers of the layer composite adjacent to the printed layers are formed from polycarbonate.

For the printing on polycarbonate composite layers basically all customary inks can be used. Preference is given to the use of a preparation comprising: A) 0.1 to 20 wt .-% of a binder with a polycarbonate derivative, B) 30 to 99.9 wt .-% of a preferably organic solvent or solvent mixture, C) 0 to 10 wt D) 0 to 10% by weight of a functional material or a mixture of functional materials, E) 0 to 30% by weight of additives and / or auxiliaries , or a mixture of such substances, wherein the sum of the components A) to E) always gives 100 wt .-%, as a printing ink. Such polycarbonate derivatives are highly compatible with polycarbonate materials, in particular with polycarbonates based on bisphenol A, such as, for example, Makrofol® films. In addition, the polycarbonate derivative used is stable to high temperatures and shows no discoloration at lamination-typical temperatures up to 200 ° C and more, whereby the use of the above-described low-Tg materials is not necessary. In particular, the polycarbonate derivative may contain functional carbonate structural units of the formula (I)

(I)

wherein R ¹ and R ² independently of one another are hydrogen, halogen, preferably chlorine or bromine, C ₁ -C ₈ -alkyl, C ₅ -C ₆ -cycloalkyl, C ₆ -C ₁₀ -aryl, preferably phenyl, and C ₇ -C ₁₂ -Aralkyl, preferably phenyl-CrC _t -alkyl, in particular benzyl, are; m is an integer from 4 to 7, preferably 4 or 5; R ³ and R ^{4 are} individually selectable for each X, independently of one another is hydrogen or C ₁ -C ₆ -alkyl; X is carbon and n is an integer greater than 20, with the proviso that on at least one atom X, R ³ and R ^{4 are} simultaneously alkyl. It is preferred for X, R ³ and R ^{4 to be} simultaneously alkyl at 1 to 2 atoms, in particular only at one atom. R ³ and R ⁴ may be in particular methyl. The X atoms in the σ position to the diphenyl-substituted C atom (C1) may not be dialkyl-substituted. The X atoms in the C1 position to C1 can be disubstituted with alkyl. Preferably m = 4 or 5. The polycarbonate derivative can be prepared, for example, on the basis of monomers, such as 4,4 ^' - (3,3,5-trimethylcyclohexane-1, 1-diyl) -diphenol, 4,4 ^' - (3,3-) dimethylcyclohexane-1, 1-diyl) diphenol, or 4,4 ^' - (2,4,4-trimethylcyclopentane-1,1-diyl) diphenol. Such a polycarbonate derivative can be prepared, for example, according to the document DE-A 38 32 396 from diphenols of the formula (Ia), the disclosure content of which is hereby incorporated in full in the disclosure of this description. It is possible to use both a diphenol of the formula (Ia) to form homopolycarbonates and a plurality of diphenols of the formula (Ia) to form copolycarbonates (meaning of radicals, groups and parameters, as in formula I).

(Ia)

In addition, the diphenols of the formula (Ia) may also be mixed with other diphenols, for example with those of the formula (Ib) HO - Z - OH (Ib),

be used for the preparation of high molecular weight, thermoplastic, aromatic polycarbonate derivatives.

Suitable other diphenols of the formula (Ib) are those in which Z is an aromatic radical having 6 to 30 C atoms, which may contain one or more aromatic nuclei, may be substituted, and aliphatic radicals or cycloaliphatic radicals other than those of the formula (II) Ia) or heteroatoms may contain as bridge members. Examples of the diphenols of the formula (Ib) are hydroquinone, resorcinol, dihydroxydiphenyls, bis (hydroxyphenyl) alkanes, bis (hydroxyphenyl) cycloalkanes, bis (hydroxyphenyl) sulfides, bis (hydroxyphenyl) ether, bis ( hydroxyphenyl) ketones, bis (hydroxyphenyl) sulfones, bis (hydroxyphenyl) sulfoxides, σ, σ'-bis (hydroxyphenyl) diisopropylbenzenes, and their nuclear alkylated and nuclear halogenated compounds. These and other suitable diphenols are described, for example, in US-A 3,028,365, US-A 2,999,835, US-A 3,148,172, US-A 3,275,601, US-A 2,991,273, US-A 3,271,367, US-A 3,062,781, US-A 2,970,131, US Pat. No. 2,999,846, DE-A 1 570 703, DE-A 2 063 050, DE-A 2 063 052, DE-A 2 211 956, FR-A 1 561 518 and H. Schnell in: "Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, the disclosures of which are hereby incorporated by reference in their entirety into the disclosure of the present specification. Preferred other diphenols are, for example: 4,4'-dihydroxydiphenyl, 2,2-bis- (4-hydroxyphenyl) propane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 1, 1-bis (4-hydroxyphenyl) cyclohexane, σ, σ-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 2 , 2-bis (3-methyl-4-hydroxyphenyl) -propane, 2,2-bis (3-chloro-4-hydroxyphenyl) -propane, bis (3,5-dimethyl-4-hydroxyphenyl) -methane , 2,2-bis- (3,5-dimethyl-4-hydroxyphenyl) -propane, bis- (3,5-dimethyl-4-hydroxyphenyl) -sulfone, 2,4-bis - (3,5-dimethyl-4-hydroxyphenyl) -2-methylbutane, 1, 1-bis- (3,5-dimethyl-4-hydroxyphenyl) -cyclohexane, σ, σ-bis- (3,5-dimethyl-) 4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis (3,5-dichloro-4-hydroxyphenyl) -propane and 2,2-bis (3,5-dibromo-4-hydroxyphenyl) -propane. Particularly preferred diphenols of the formula (Ib) are, for example, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dichloro-4-hydroxyphenyl) -propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) -propane and 1, 1-bis (4-hydroxyphenyl) -cyclohexane. In particular, 2,2-bis (4-hydroxyphenyl) propane is preferred. The other diphenols can be used both individually and in a mixture. The molar ratio of diphenols of the formula (Ia) to those which may optionally be used Diphenols of the formula (Ib) ₁ should be between 100 mol% (Ia) to 0 mol% (Ib) and 2 mol% (Ia) to 98 mol% (Ib) _1, preferably between 100 mol% (Ia) to 0 mol% (Ib) and 10 mol% (Ia) to 90 mol% (Ib) and especially between 100 mol% (Ia) to 0 mol% (Ib) and 30 mol% (Ia) to 70 mol% (Ib). The high molecular weight polycarbonate derivatives from the diphenols of the formula (Ia), optionally in combination with other diphenols, can be prepared by the known polycarbonate production processes. The various diphenols can be linked together both statistically and in blocks. The polycarbonate derivatives used can be branched in a manner known per se. If the branching is desired, this can in known manner by condensing small amounts, preferably amounts of 0.05 to 2.0 mol% (based on diphenols), of trifunctional or more than trifunctional compounds, especially those with three or more than three phenolic hydroxyl groups. Some branching agents having three or more than three phenolic hydroxyl groups are phloroglucinol, 4,6-dimethyl-2,4,6-tri- (4-hydroxyphenyl) -heptene-2,4,6-dimethyl-2,4,6-tri - (4-hydroxyphenyl) heptane, 1, 3,5-tri (4-hydroxyphenyl) benzene, 1,1,1-tri (4-hydroxyphenyl) ethane, tri- (4-hydroxyphenyl) phenylmethane , 2,2-bis [4,4-bis (4-hydroxyphenyl) cyclohexyl] propane, 2,4-bis (4-hydroxyphenyl-isopropyl) -phenol, 2,6-bis (2,6-bis) 2-hydroxy-5-methyl-benzyl) -4-methylphenol, 2- (4-hydroxyphenyl) -2- (2,4-dihydroxyphenyl) -propane, hexa- [4- (4-hydroxyphenyl-isopropyl) -phenyl] -orthoterephthalic acid ester, tetra (4-hydroxyphenyl) methane, tetra- [4- (4-hydroxyphenyl-isopropyl) -phenoxy] -methane and 1,4-bis- [4,4-dihydroxytriphenyl) -methyl] -benzene. Some of the other trifunctional compounds are 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride and 3,3-bis (3-methyl-4-hydroxyphenyl) -2-oxo-2,3-dihydroindole Molecular weight of the polycarbonate derivative ate serve monofunctional compounds in conventional concentrates. Suitable compounds are, for example, phenol, tert-butylphenols or other alkyl-substituted phenols. For controlling the molecular weight, in particular small amounts of phenols of the formula (Ic) are suitable

(Ic) wherein R represents a branched C ₈ and / or C ₉ alkyl radical. Preferably, in the alkyl radical R, the proportion of CH ₃ protons between 47 and 89% and the proportion of CH and CH ₂ - protons between 53 and 11%; also preferably R is in the o- and / or p-position to the OH group, and more preferably the upper limit of the ortho-portion is 20%. The chain terminators are generally used in amounts of 0.5 to 10, preferably 1, 5 to 8 mol%, based on diphenols used. The polycarbonate derivatives can preferably be prepared in a manner known per se by the phase interface behavior (compare H. Schnell in: Chemistry and Physics of Polycarbonates, Polymer Reviews, Vol. IX, page 33 et seq., Interscience Publ. In this case, the diphenols of the formula (Ia) are dissolved in an aqueous alkaline phase. For the preparation of copolycarbonates with other diphenols, mixtures of diphenols of the formula (Ia) and the other diphenols, for example those of the formula (Ib), are used. To regulate the molecular weight, chain terminators of, for example, the formula (Ic) can be added. Then, in the presence of an inert, preferably polycarbonate-dissolving, organic phase is reacted with phosgene by the method of interfacial condensation. The reaction temperature is in the range from ⁰ ° C. to 40 ^° C. The branching agents which may be used (preferably 0.05 to 2.0 mole%) may be initially charged with the diphenols in the aqueous alkaline phase or dissolved in the organic solvent be added before phosgenation. In addition to the diphenols of the formula (Ia) and, if appropriate, other diphenols (Ib), their mono- and / or bis-chlorocarbonic acid esters may also be used, these being added dissolved in organic solvents. The amount of chain terminators and of branching agents then depends on the molar amount of diphenolate radicals corresponding to formula (Ia) and optionally formula (Ib); When using chloroformates the amount of phosgene can be reduced accordingly in a known manner. Suitable organic solvents for the chain terminators and optionally for the branching agents and the chloroformates are, for example, methylene chloride, chlorobenzene and in particular mixtures of methylene chloride and chlorobenzene. Optionally, the chain terminators and branching agents used can be dissolved in the same solvent. For example, methylene chloride, chlorobenzene and mixtures of methylene chloride and chlorobenzene serve as the organic phase for the interfacial polycondensation. The aqueous alkaline phase used is, for example, NaOH solution. The preparation of the polycarbonate derivatives by the interfacial process can in the usual way by catalysts such as tertiary amines, in particular tertiary aliphatic amines, such as Tributylamine or triethylamine; the catalysts can be used in amounts of 0.05 to 10 mol%, based on moles of diphenols used. The catalysts can be added before the beginning of the phosgenation or during or after the phosgenation. The polycarbonate derivatives can be prepared by the known method in the homogeneous phase, the so-called "pyridine process" and by the known melt transesterification process using, for example, diphenyl carbonate instead of phosgene. The polycarbonate derivatives may be linear or branched, they are homopolycarbonates or copolycarbonates based on the diphenols of the formula (Ia). By arbitrary composition with other diphenols, in particular with those of the formula (Ib), the polycarbonate properties can be varied in a favorable manner. In such copolycarbonates, the diphenols of the formula (Ia) are present in amounts of from 100 mol% to 2 mol%, preferably in amounts of from 100 mol% to 10 mol% and in particular in amounts of from 100 mol% to 30 mol% %, based on the total amount of 100 mol% of diphenol units contained in polycarbonate derivatives. The polycarbonate derivative may be a copolymer containing, in particular consisting thereof, monomer units M1 based on the formula (Ib). Preferably bisphenol A, and monomer units M2 based on the geminally disubstituted dihydroxydiphenylcycloalkane, preferably the 4,4 ^' - (3,3,5 - Trimethylcyclohexan-1, 1-diyl) diphenols, wherein the molar ratio M2 / M1 is preferably greater than 0.3, in particular greater than 0.4, for example greater than 0.5. It is preferred that the polycarbonate derivative has a weight average molecular weight of at least 10,000, preferably from 20,000 to 300,000.

In principle, component B may be substantially organic or aqueous. Substantially aqueous means that up to 20% by weight of component B) can be organic solvents. Substantially organic means that up to 5% by weight of water may be present in component B). Component B preferably contains one or consists of a liquid aliphatic, cycloaliphatic and / or aromatic hydrocarbon, a liquid organic ester and / or a mixture of such substances. The organic solvents used are preferably halogen-free organic solvents. Particularly suitable are aliphatic, cycloaliphatic, aromatic hydrocarbons, such as mesitylene, 1, 2,4-trimethylbenzene, cumene and solvent naphtha, toluene, xylene; (organic) esters such as methyl acetate, ethyl acetate, butyl acetate, methoxypropyl acetate, ethyl 3-ethoxypropionate. Preference is given to mesitylene, 1, 2,4-trimethylbenzene, cumene and solvent naphtha, toluene, Xylene, methyl acetate, ethyl acetate, methoxypropyl acetate. Ethyl 3-ethoxypropionate. Most particularly preferred are mesitylene (1, 3,5-trimethylbenzene), 1, 2,4-trimethylbenzene, cumene (2-phenylpropane), solvent naphtha and ethyl 3-ethoxypropionate. A suitable solvent mixture comprises, for example, L1) 0 to 10% by weight, preferably 1 to 5% by weight, in particular 2 to 3% by weight, mesitylene, L2) 10 to 50% by weight, preferably 25 to 50% by weight %, in particular 30 to 40% by weight, 1-methoxy-2-propanol acetate, L3) 0 to 20% by weight, preferably 1 to 20% by weight, in particular 7 to 15% by weight, 1 , 2,4-trimethylbenzene, L4) 10 to 50 wt.%, Preferably 25 to 50 wt.%, In particular 30 to 40 wt.%, Ethyl 3-ethoxypropionate, L5) 0 to 10 wt. , preferably 0.01 to 2 wt .-%, in particular 0.05 to 0.5 wt .-%, cumene, and L6) 0 to 80 wt .-%, preferably 1 to 40 wt .-%, in particular 15 to 25 wt .-%, solvent naphtha, wherein the sum of components L1 to L6 always gives 100 wt .-%.

The preparation may contain in detail: A) 0.1 to 10 wt .-%, in particular 0.5 to 5 wt .-%, of a binder with a polycarbonate derivative based on a geminal disubstituted dihydroxydiphenylcycloalkane, B) 40 to 99.9 wt %, in particular 45 to 99.5% by weight, of an organic solvent or solvent mixture, C) 0.1 to 6% by weight, in particular 0.5 to 4% by weight, of a colorant or colorant mixture, D ) 0.001 to 6 wt .-%, in particular 0.1 to 4 wt .-%, of a functional material or a mixture of functional materials, E) 0.1 to 30% by weight, in particular 1 to 20 wt .-%, Additives and / or auxiliaries, or a mixture of such substances.

As component C, if a colorant is to be provided, basically any colorant or colorant mixture comes into question. Colorants are all colorants. This means that it can be both dyes (an overview of dyes Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release 2007, Wiley publishing house, chapter "Dyes, General Survey") as well as pigments (a review of organic and inorganic pigments is Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release 2007, Wiley Verlag, chapter "Pigments, Organic" and "Pigments, Inorganic") act. Dyes should be soluble or (stably) dispersible or suspendible in the component B solvents. Furthermore, it is advantageous if the colorant at temperatures of 16O ⁰ C and more for a period of more than 5 min. stable, in particular color-stable, is. It is also possible that the colorant of a given and reproducible Color change is subjected to the processing conditions and selected accordingly. In addition to the temperature stability, pigments must be present in particular in the finest particle size distribution. For inkjet printing, this means in practice that the particle size should not exceed 1, 0 microns, otherwise blockages in the printhead are the result. As a rule, nanoscale solid-state pigments and dissolved dyes have proven their worth. The colorants may be cationic, anionic or even neutral. Only examples of colorants which can be used in ink-jet printing are: Brilliant black Cl. No. 28440, Chromogen Black Cl. No. 14645, direct deep black E Cl. No. 30235, true black salt B Cl. No. 37245, true black salt K Cl. No. 37190, Sudan Black HB Cl. 26150, Naphtol Black Cl. No. 20470, Bayscript® Black Liquid, Cl. Basic Black 11, Cl. Basic Blue 154, Cartasol® Turquoise K-ZL liquid, Cartasol® Turquoise K-RL liquid (Cl. Basic Blue 140), Cartasol Blue K5R liquid. Also suitable are, for example, the commercially available dyes Hostafine® Black TS liquid (sold by Clariant GmbH Germany), Bayscript® Black Liquid (Cl mixture, sold by Bayer AG Germany), Cartasol® Black MG liquid (CI Basic Black 11, Registered Trade Mark of Clariant GmbH Germany), Flexonyl Black® PR 100 (E Cl. No. 30235, marketed by Hoechst AG), Rhodamine B, Cartasol® Orange K3 GL, Cartasol® Yellow K4 GL, Cartasol® K GL, or Cartasol ® Red K-3B. Furthermore, anthraquinone, azo, quinophthalone, coumarin, methine, perinone, and / or pyrazole dyes, eg available under the trade name Macrolex®, can be used as soluble colorants. Further suitable colorants are described in the reference Ullmann ^'s Encyclopedia of Industrial Chemistry, Electronic Release 2007, Wiley Verlag, chapter "Colorants Used in Ink Jet Inks". Well-soluble colorants lead to an optimal integration into the matrix or the binder of the print layer. The colorants may be added either directly as a dye or pigment or as a paste, a mixture of dye and pigment together with another binder. This additional binder should be chemically compatible with the other components of the formulation. If such a paste is used as a colorant, the amount of component B refers to the colorant without the other components of the paste. These other components of the paste are then subsumed under the component E. When using so-called colored pigments in the scale colors cyan-magenta-yellow and preferably also (soot) black solid color images are possible. Component D comprises substances that can be seen directly by the human eye or by the use of suitable detectors using technical aids. By this is meant the materials known to those skilled in the art (see also van Renesse in: "Optical document security", 3rd ed., Artech House, 2005), which are used to secure value and security documents, including luminescent substances (dyes or pigments , organic or inorganic), such as, for example, photoluminophores, electroluminophores, Antistokes luminophores, fluorophores, but also magnetizable, photoacoustically addressable or piezoelectric materials, or Raman-active or Raman-enhancing materials, as well as so-called barcode materials as preferred criteria, either the solubility in the component B or pigmented systems particle sizes <1 micron and a temperature stability for temperatures> 160 ⁰ C in the sense of the comments on the component C. Functional materials can be added directly or via a paste, ie a mixture with another binder el, which then forms part of component E, or the binder used in component A.

Component E in inks for ink-jet printing includes conventionally prepared materials such as anti-foaming agents, modifiers, wetting agents, surfactants, flow agents, dryers, catalysts, (light) stabilizers, preservatives, biocides, surfactants, organic polymers for viscosity adjustment, buffer systems, etc. As setting agents customary setting salts come into question. An example of this is sodium lactate. As biocides, all commercially available preservatives which are used for inks come into question. Examples are Proxel® GXL and Parmetol® A26. Suitable surfactants are all commercially available surfactants which are used for inks. Preferred are amphoteric or nonionic surfactants. Of course, it is also possible to use special anionic or cationic surfactants which do not alter the properties of the dye. Examples of suitable surfactants are betaines, ethoxylated diols, etc. Examples are the product series Surfynol® and Tergitol®. The amount of surfactants is especially selected when used for ink-jet printing, for example, provided that the surface tension of the ink is in the range of 10 to 60 mN / m, preferably 20 to 45 mN / m, measured at 25 ^° C. A buffer system can be set up which stabilizes the pH in the range from 2.5 to 8.5, in particular in the range from 5 to 8. Suitable buffer systems are lithium acetate, borate buffer, triethanolamine or acetic acid / sodium acetate. One Buffer system will come in particular in the case of a substantially aqueous component B in question. To adjust the viscosity of the ink (possibly water-soluble) polymers can be provided. Here all suitable for conventional ink formulations polymers come into question. Examples are water-soluble starch, in particular with an average molecular weight of 3,000 to 7,000, polyvinylpyrrolidone, in particular with an average molecular weight of 25,000 to 250,000, polyvinyl alcohol, in particular with an average molecular weight of 10,000 to 20,000, xanthan gum, carboxymethylcellulose, ethylene oxide / propylene oxide Block copolymer, especially having an average molecular weight of 1,000 to 8,000. An example of the latter block copolymer is the product series Pluronic®. The proportion of biocide, based on the total amount of ink, may be in the range of 0 to 0.5% by weight, preferably 0.1 to 0.3% by weight. The proportion of surfactant, based on the total amount of ink, can range from 0 to 0.2 wt .-%. The proportion of adjusting agents, based on the total amount of ink, 0 to 1 wt .-%, preferably 0.1 to 0.5 wt .-%, amount. The auxiliaries also include other components, such as, for example, acetic acid, formic acid or n-methylpyrolidone or other polymers from the dye solution or paste used. With regard to substances which are suitable as component E, reference is additionally made, for example, to Ullmann's Encyclopedia of Chemical Industry, Electronic Release 2007, Wiley Verlag, chapter "Paints and Coatings", section "Paint Additives".

The above-described ink composition is particularly suitable for ink-jet printing, but may be used for any other printing technique as long as the ratio of the individual components to the application is adjusted. It is essential in this connection that the described composition contains as binder a polycarbonate derivative if the polymer material layers of the composite likewise consist of polycarbonate.

More generally, regardless of whether or not the above-described printing materials (especially inks) are used, it is preferable that the image information is formed by pixels (pixels) of ink-jet printing at least in one of the layers having watermark information. Such a printed image is particularly well suited for introducing digital watermarks into image information. For example, the watermark can be introduced into the image information by changing the shape, size and / or composition of pixels of the printed image. For example, a pixel composed of a plurality of sub-areas of predefined shape and / or size may encode a pixel that is part of the watermark information. If a pixel has a different shape, it may be z. B. not for watermark information.

Embodiments of the invention will now be described with reference to the accompanying drawings. The individual figures of the drawing show:

1 shows an exploded view of a document from the side,

2 shows a document in perspective exploded view,

3 is a flowchart for illustrating a first embodiment of a

4 shows a flow chart for illustrating a further exemplary embodiment of an authentication method, and FIG. 5 shows a representation of a further security feature based on a predefined, intentionally fuzzy display of image objects.

Fig. 1 shows five layers 3, 5, 7, 9, 11 of a document 1 in exploded view from the side, i. the uppermost layer 3 and the lowermost layer 11 form the outer surfaces of the document 1. The representation can also be understood as representing an intermediate step in the production of the document 1. In this case, Fig. 1 shows the state immediately before laminating the layers 3-11.

Three inner layers 5, 7, 9 of the document 1 each have a portion 15, 17, 19 on its lower surface. In each of these subareas 15, 17, 19, image information in the form of a printed image, preferably an inkjet print image, is printed. Preferably, each of the print images is executed in a single base color of a multi-component color system, e.g. RGB or CMYK. As shown by three interleaved points on the left in Fig. 1, which are located between the layer 7 and the layer 9, the document may have further layers, which may also be printed in partial areas, e.g. with the missing fourth color of the CMYK color space.

The printed subregions 15, 17, 19 are thus positioned in the layers 5, 7, 9 and are arranged before lamination to each other so that the printed images in the Subregions 15, 17, 19 when viewing the outer surface (from below and / or from above) of the document 1 give an overall picture. In the case of the color systems mentioned, therefore, the overall picture is generally multi-colored.

At least two of the partial areas 15, 17, 19 each contain watermark information in the printed image. In this case, the watermark information is preferably executed as information of a digital watermark, which is not perceptible to a viewer or can only be perceived with technical aids.

In the layers 5, 7, 9 shown in Fig. 2, e.g. to act the layers of the document 1 of FIG. 1. These layers in turn have a portion 15, 17, 19, which is printed with image information. In the exemplary embodiment illustrated here, each of the regions 15, 17, 19 has a subregion 25, 27, 29 which contains watermark information. Outside these subregions 25, 27, 29, image information is likewise present, but no watermark information. As also shown in FIG. 2, these subregions 25, 27, 29 do not overlap one another after the precise lamination of the layers 5, 7, 9. Even if the ignorant viewer or potential counterfeiter should recognize a watermark when viewing the surface of the document 1, he does not notice that the overall watermark information is distributed over the three layers of the layers 5, 7, 9. For example, if the thicknesses of the layers 5, 7, 9 are about 50 μm, it is not possible without prior knowledge (for example via the assignment of the colors to the layers) to recognize that the watermark information is distributed over the layers. The same applies, of course, also for the case that watermark information is arranged in different layers so that it lies one above the other. For example, For example, the partial regions 25, 27, 29 could completely or partially overlap, the concept of overlapping assuming that the regions 15, 17, 19 are viewed from above or below in the illustration of FIG. 2.

Exemplary embodiments for the evaluation of the watermark information will now be described with reference to FIGS. 3 and 4. Even if only the evaluation and the acquisition of the watermark information are described here, there are thus direct indications as to how the document is produced or manufactured with regard to the introduction of the watermark information. FIG. 3 shows a document 1 in the upper left in the image, which may be, for example, the document described in FIG. 1 and / or FIG. In a first step 31, first watermark information is acquired from a print image 15 of the document 1. For example, first the entire image information in the print image 15 is detected. However, this is merely the image information in a first layer of document 1. For example, the entire print image in the layer is printed in a single color (eg, yellow). The watermark information can then be extracted from the printed image by methods known per se, for example using predefined evaluation rules. The extraction of the first watermark information is shown in FIG. 3 by block 33.

In a following step 35, the first watermark information is fed to an evaluation 37. However, this is only a part of the total watermark information contained in the document 1 before.

When this application is concerned with an overall image formed by image information in multiple layers, the image need not be an image in a continuous area. Rather, the invention also covers cases in which a plurality of images or partial images are distributed over the area of the document that offers the viewer. The watermark information can also be distributed over these multiple images or partial images.

In step 39, image information which also contains watermark information is acquired from a second layer in which the print image 17 is located. For example, In the manner already described, second watermark information is thus obtained in step 41, which is fed to the evaluation 37 in step 43.

As shown below in FIG. 3, image information is also acquired from a print image 19 from a third layer of the document 1 (step 45), third watermark information is extracted (step 47) and the third watermark information is supplied to the evaluation 37 in step 49.

The operation of the evaluation 37, which serves to determine whether the document 1 is authentic or not, will be discussed in more detail after FIG. 4 has been described. For the procedure described with reference to FIG. 3, there are numerous variants. For example, the watermark information may be extracted from a different number of layers (eg, two or four layers of document 1). The image areas in which the watermark information is located in the individual layers may completely or partially overlap one another or they may not overlap one another. Furthermore, the total information required for the authentication may not be contained exclusively in the image composed by the partial print images in the individual layers. Rather, further information contained in the document can be combined together with the watermark information contained in the image into an overall information, it being this total information that enables the decision as to whether the document is authentic. Examples of how further information can be contained in the document are digital data memories (eg a memory chip) and optically recognizable information which optionally can also be encoded, eg in the MRZ (Machine Readable Zone).

4 shows an exemplary embodiment with evaluation of print image information in only two different layers of a document 1. In a first step, print image information is acquired from a print image 15 in a first layer (step 51). In step 53, first watermark information is extracted therefrom. The procedure now differs from the method according to FIG. 3 in that information obtained from the first watermark information in step 55 is used to control the acquisition and / or evaluation of further watermark information. For example, The first watermark information contains information about where second watermark information is to be detected in the document, i. For example, in which partial area of which layer of the document 1 the second watermark information is contained. In this case, the layer can be defined by the assigned color.

In step 59, image information is acquired using the information from step 55 in a second layer having a print image 17, and in step 61 the searched second watermark information is extracted.

Like the printed images 15, 17, 19 according to FIG. 3, the printed images 15, 17 according to FIG. 4 in a preferred embodiment can each consist of a single color Be formed color system. Above, mention has already been made of print image 15 in FIG. 3 that the printed image is formed, for example, from printing materials of yellow color. The printed images 17 according to FIG. 3 and FIG. 4 are accordingly formed, for example, from printing materials of the color magenta.

The first and second watermark information extracted in steps 53, 61 are fed to the evaluation 37 in steps 57, 63.

The procedure described with reference to FIG. 4 can also be modified. In particular, it can also be combined with the procedure described with reference to FIG. 3. So it is e.g. it is possible to detect and extract watermark information from different layers completely independently of one another and also to use watermark information of individual layers to find, capture and extract watermark information in other layers. Furthermore, in the evaluation 37, which will be described in more detail, watermark information from individual subregions or individual layers can be used to control the evaluation of watermark information from other layers or the overall watermark information.

In a simple case, the evaluation 37 proceeds as follows: As shown in Figure 3, each of the watermark information in each layer contains a digital watermark that contains separate information independent of the other watermarks. For example, the name of the document owner is determined from the first watermark information, the date of birth of the document owner is determined from the second watermark information, and the document number is determined from the third watermark information. This information can now be matched with plain text on the document or e.g. from the MRZ of the document. Voices e.g. Name, date of birth or document number do not match, the document is not authentic.

Quite generally, in the case of the present invention, the watermark information can be encrypted, so that it can only be obtained from the watermark if the key is known. Also, for example, a cryptographic hash function has been applied for generating the watermark information so that from the watermark information can not be deduced the original, the watermark underlying information. In this case, during the evaluation, for example, the original information is also used to generate a comparison information for checking the authenticity using the hash function. Furthermore, the information contained in the watermark may, for example, have been signed with a signature of the issuer in order to unambiguously prove the origin.

In another variant of the evaluation of the total watermark information, the total information may be e.g. from the sum or other predetermined logical association of the individual watermark information. For example, For example, bit sequences obtained from the first, second and third watermarks according to FIG. 3 can be strung together in a predefined manner so that a single overall bit sequence is obtained.

According to a further possibility of the evaluation, whereby the evaluation in this case also means the detection and extraction of the individual watermark information, (as mentioned above) already extracted watermark information is used to control e.g. the decryption of watermark information, the order of extraction of watermark information and / or the evaluation of other watermark information in the same document and / or used to determine redundant information. Also, the already extracted watermark information may specify the evaluation method to be used (e.g., transformation from the color amplitude space to the frequency space).

In the cases mentioned above, each case may be cases in which the information contained in the individual watermark information is independent information that can therefore be evaluated on its own. But it is also possible that only after detection and extraction of a plurality of watermark information in different sub-areas of the same layer and / or in different layers, a total information is obtained, which can be evaluated. In this case, the partial information, which is composed to the evaluable total information, as mentioned, each of a color and / or layer to be assigned. Mixed forms are also possible in which a part of the watermark information (eg the watermark information in the layer which is assigned the color yellow) can be evaluated by itself and independently of the further watermark information and watermark information from other planes (eg a second plane containing the color Magenta is assigned and a third level, which is associated with the color cyan) is evaluable only if the entire information consists of two or more layers. The mixed forms can also be designed so that an already extracted part of the total watermark information of all layers controls the acquisition, extraction and / or evaluation. By "controlling" is not understood that the information necessarily controls the process alone. Rather, it is understood that, for example, a software controls the process using the already extracted watermark information.

Another idea to be described here is that with the above-described idea of introducing watermark information into several layers of a document, it can be combined or else it can be implemented independently of this.

The idea is based on the problem that counterfeiters today also have very high-resolution optical scanners. In order to be able to provide a further security feature in a document, it is proposed that an optically readable information (eg a font symbol or another symbol, a logo or a graphic, a barcode and / or a watermark, in particular a digital watermark) in accordance with a default rule in the document are introduced blurred. Blurred is understood to mean that the color intensity profile at the edge of the respective object to be printed (symbol, etc., see above) is slower, ie. decreases to zero or to a different intensity value over a greater length than is the case in the information without the blur operation.

In extreme cases, this blurring operation can cause the information to no longer be recognized by the viewer. For example, it is conceivable to form intensity maxima and minima of a printing ink on the document in a similar geometric distribution as in a guilloche pattern, the intensity maxima lying, for example, where the guilloche lines usually run and where the minima of intensity are, for example, where usually the middle is located between two guilloche lines. If the intensity maximum is chosen to be low enough and the blur selected to be large enough, ie the transition from intensity maximum to intensity minimum occurs with little decrease in intensity per unit length, the pattern thus obtained or the information thus obtained is not or only in the document Shading recognizable.

After the optical detection of the print image, using the knowledge of how the original information was changed by the blur operation, the original information can be calculated. For example, is determined using thresholds for the color intensity along an evaluation direction, when a threshold is reached or exceeded or reached or fallen below and the place where the threshold is reached, undershot or exceeded, defined as the edge of an area to be identified. Another possibility is to determine the intensity profile along an evaluation direction, e.g. by calculating the intensity gradient as a function of the location to determine and to calculate a corresponding print image, in which the intensity curve is much steeper.

In particular, the intensity can be varied by printing more or less (and / or larger or smaller) pixels of a color per unit area in digital printing.

This notion of blur operation is now combined with one or more features of the invention as described above with respect to the arrangement of image information in different layers of a document. The image information does not necessarily have to contain watermark information. However, it is possible that at least one layer also contains watermark information.

It is now proposed that the blur operation be performed only in one or more but not all layers containing image information for an overall image.

An embodiment is shown in Fig. 5. The upper part of the figure shows the letter "A" on the left in sharp representation, in the middle after the application of a first blur operation and on the right after application of a second one Blur operation, where the first blur operation results in less blur than the second blur operation.

The lower part of FIG. 5 shows in each case one overall printed image for one of the three representations of the letter "A" in the upper part, the letter "A" being printed in a first layer of a document and also recognizable in FIG. 5 below Alphabet is additionally printed with the numbers 1 to 4 in a second, different from the first level level. In this case, the different levels or layers can each again be associated with a color of a color system. If e.g. If the letter "A" is printed in the color yellow and the alphabet in the color black, the letter "A" will be even less recognizable if the second blurring operation has been applied to it (bottom right in FIG. 5).

As the diagonal hatching in the lower part of Fig. 5 indicates, e.g. in the layer of the letter "A" or in the layer of the alphabet or in another layer of the document, an additional hatching is printed which further reduces the recognizability of the letter "A".

It is also possible to incorporate the information which has been subjected to the blurring operation into a layer of a multi-layered printed image in which also sharply printed information is contained.

Claims

claims

A method of manufacturing a document (1), wherein

in each case image information is introduced into a plurality of layers (15, 17, 19) of the document (1) so that the image information complements an overall image,

- the image information in at least two of the layers (15, 17, 19) contains digital watermark information (25, 27, 29), wherein first the entirety of the digital watermark information (25, 27, 29) in the at least two layers (15, 17, 19) constitutes a security feature for authentication of the document (1).

2. Method according to the preceding claim, wherein in at least one of the layers (15, 17, 19) watermark information (25, 27, 29) is introduced into a partial area of the image area.

3. Method according to the preceding claim, wherein the watermark information (25, 27, 29) in a first layer (15) contains information about in which subarea other watermark information is arranged in the first layer or in a second layer (17).

4. Method according to one of the preceding claims, wherein watermark information (25, 27, 29) in a first layer (15) contains information about how watermark information is to be evaluated in a second layer (17) and / or in another subregion of the first layer ,

5. The method according to any one of the preceding claims, wherein watermark information (25, 27, 29), which is introduced in different layers (15, 17, 19), only in its entirety forms an evaluable authentication information.

6. The method according to any one of the preceding claims, wherein the watermark information in different layers (15, 17, 19) is introduced such that they in a non-selective to a single layer related optical detection of the image information is a first Forms total information and in a selectively on the individual layers (15, 17, 19) related optical detection of the image information forms a second total information, which is different from the first total information.

7. The method according to any one of the preceding claims, wherein a plurality of adjacent layers (5, 7, 9) of the document (1) are each formed by a polymer material and the adjacent layers (5, 7, 9) are firmly connected to each other, so that they Layers (5, 7, 9) form a Polymermateriallagenverbund.

8. The method according to the preceding claim, wherein at least two of the adjacent layers (5, 7, 9) are formed of polycarbonate material.

9. The method according to any one of the preceding claims, wherein the image information is formed in at least one of the layers (15, 17, 19) by printing materials containing polycarbonate-based binders.

10. The method according to any one of the preceding claims, wherein the image information in the individual layers (15, 17, 19) of the document (1) is represented by a different color.

11. The method according to any one of the preceding claims, wherein the image information in at least one of the layers (15, 17, 19), which has a watermark information (25, 27, 29) is formed by pixels of an ink jet printing.

12. Document, in particular value and / or security document, wherein

- The document has a plurality of layers (15, 17, 19), in each of which image information is introduced, so that the image information complements an overall image,

the image information in at least two of the layers (15, 17, 19) contains watermark information (25, 27, 29), wherein only the entirety of the watermark information (25, 27, 29) in the at least two layers (15, 17, 19) forms a security feature for an authentication of the document (1).

13. Document according to the preceding claim, wherein in at least one of the layers (15, 17, 19) watermark information (25, 27, 29) is introduced into a partial region of the image surface.

The document of claims 10 and 11, wherein the watermark information (25) in a first layer (15) contains information about which portion other watermark information (27) is located in the first layer or in a second layer (17).

Document according to one of the preceding claims, wherein watermark information (25, 27, 29) in a first layer (15) contains information about it, such as watermark information (25, 27, 29) in a second layer (17) and / or in a second layer other subarea of the first layer is evaluated.

16. Document according to one of the preceding claims, wherein watermark information (25, 27, 29), which is introduced in different layers (15, 17, 19), only in its entirety forms an evaluable authentication information.

17. A document according to any one of the preceding claims, wherein the watermark information (25, 27, 29) in different layers (15, 17, 19) is introduced so that they in a non-selective to a single layer related optical detection of the image information a first Forms total information and in a selectively on the individual layers (15, 17, 19) related optical detection of the image information forms a second total information, which is different from the first total information.

18. Document according to one of the preceding claims, wherein a plurality of adjacent layers (5, 7, 9) of the document (1) in each case by a Polymer material are formed and the adjacent layers (5, 7, 9) are firmly connected to each other, so that these layers (5, 7, 9) form a Polymermateriallagenverbund.

19. Document according to the preceding claim, wherein at least two of the adjacent layers (5, 7, 9) comprise polycarbonate material.

Document according to one of the preceding claims, wherein the image information in at least one of the layers (15, 17, 19) is formed by printing materials containing polycarbonate-based binders.

21. Document according to one of the preceding claims, wherein the image information in the individual layers (15, 17, 19) of the document (1) is represented by a different color.

A document according to any one of the preceding claims, wherein the image information is formed by at least one of the layers (15, 17, 19) having watermark information (25, 27, 29) by pixels of ink-jet printing.

23. Authentication method for determining whether a document is authentic, wherein

in each case image information is acquired in a plurality of layers (15, 17, 19) of the document (1), the image information of the different layers (15, 17, 19) being supplemented to form an overall image,

in each case watermark information (25, 27, 29) is extracted from the image information in at least two of the layers (15, 17, 19),

it is determined from the entirety of the extracted watermark information (25, 27, 29) of the at least two layers (15, 17, 19) whether the document is authentic.

24. Authentication method according to the preceding claim, wherein in at least one of the layers (15, 17, 19) watermark information (25, 27, 29) is detected in a partial area of the image area.

25. Authentication method according to the preceding claim, wherein it is determined from watermark information (25) in a first layer (15) in which subarea other watermark information (27) is arranged in the first layer or in a second layer (17).

26. Authentication method according to one of the preceding claims, wherein watermark information (25) in a first layer (15) is used to evaluate watermark information (27) in a second layer (17) and / or in another subregion of the first layer is.

27. Authentication method according to one of the preceding claims, wherein watermark information (25, 27, 29) in different layers (15, 17, 19) is detected, which forms only in its entirety an evaluable authentication information.

28. Authentication method according to one of the preceding claims, wherein image information in different layers (15, 17, 19) is non-selectively optically detected with respect to a single layer, from which a first watermark information is extracted, which forms a first overall information, wherein furthermore image information with respect to the individual layers (15, 17, 19) is optically detected, based on the individual layers (15, 17, 19) related watermark information is extracted, which form a second total information, and wherein by evaluating the first total information and the second Overall information is determined as to whether the document is authentic.

29. Authentication method according to one of the preceding claims, wherein the image information in at least one of the layers (15, 17, 19) of the document (1) is detected by selective detection of image signals in a predetermined color associated with the layer.

The authentication method according to any one of the preceding claims, wherein the image information is detected in at least one of the layers (15, 17, 19) having watermark information (25, 27, 29) by detecting a pixel structure of ink jet printing in the layer is detected.

31. An authentication device for determining whether a document is authentic, the device comprising:

a detection device which is designed to detect image information in a plurality of layers (15, 17, 19) of the document (1), wherein the image information of the different layers (15, 17, 19) complements an overall image,

an extraction device configured to extract watermark information (25, 27, 29) from the image information in at least two of the layers (15, 17, 19),

- A determination device, which is configured, from the entirety of the extracted watermark information (25, 27, 29) of the at least two layers (15, 17, 19) to determine whether the document is authentic.

32. An authentication device configured to execute the authentication method according to any one of claims 23 to 30.